[interpreter, debugger] support debug breaks via bytecode array copy

src/arm64/builtins-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/arm64/frames-arm64.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
@@ skipping 854 matching lines @@
   // Open a frame scope to indicate that there is a frame on the stack.  The
   // MANUAL indicates that the scope shouldn't actually generate code to set up
   // the frame (that is done below).
   FrameScope frame_scope(masm, StackFrame::MANUAL);
   __ Push(lr, fp, cp, x1);
   __ Add(fp, jssp, StandardFrameConstants::kFixedFrameSizeFromFp);
 
   // Get the bytecode array from the function object and load the pointer to the
   // first entry into kInterpreterBytecodeRegister.
   __ Ldr(x0, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
+  Register debug_info = kInterpreterBytecodeArrayRegister;
+  Label load_debug_bytecode_array, bytecode_array_loaded;
+  DCHECK(!debug_info.is(x0));
+  __ Ldr(debug_info, FieldMemOperand(x0, SharedFunctionInfo::kDebugInfoOffset));
+  __ Cmp(debug_info, Operand(DebugInfo::uninitialized()));
+  __ B(ne, &load_debug_bytecode_array);
   __ Ldr(kInterpreterBytecodeArrayRegister,
          FieldMemOperand(x0, SharedFunctionInfo::kFunctionDataOffset));
+  __ Bind(&bytecode_array_loaded);
 
   if (FLAG_debug_code) {
     // Check function data field is actually a BytecodeArray object.
     __ AssertNotSmi(kInterpreterBytecodeArrayRegister,
                     kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
     __ CompareObjectType(kInterpreterBytecodeArrayRegister, x0, x0,
                          BYTECODE_ARRAY_TYPE);
     __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
   }
 
@@ skipping 49 matching lines @@
                          kInterpreterBytecodeOffsetRegister));
   __ Mov(x1, Operand(x1, LSL, kPointerSizeLog2));
   __ Ldr(ip0, MemOperand(kInterpreterDispatchTableRegister, x1));
   // TODO(rmcilroy): Make dispatch table point to code entrys to avoid untagging
   // and header removal.
   __ Add(ip0, ip0, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ Call(ip0);
 
   // Even though the first bytecode handler was called, we will never return.
   __ Abort(kUnexpectedReturnFromBytecodeHandler);
+
+  // Load debug copy of the bytecode array.
+  __ Bind(&load_debug_bytecode_array);
+  __ Ldr(kInterpreterBytecodeArrayRegister,
+         FieldMemOperand(debug_info, DebugInfo::kAbstractCodeIndex));
+  __ B(&bytecode_array_loaded);
 }
 
 
 void Builtins::Generate_InterpreterExitTrampoline(MacroAssembler* masm) {
   // TODO(rmcilroy): List of things not currently dealt with here but done in
   // fullcodegen's EmitReturnSequence.
   //  - Supporting FLAG_trace for Runtime::TraceExit.
   //  - Support profiler (specifically decrementing profiling_counter
   //    appropriately and calling out to HandleInterrupts if necessary).
 
@@ skipping 1738 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM